The present invention relates to an ink jet recording unit for recording by ejecting ink. More particularly, the invention relates to an ink jet recording unit which is formed with a recording head and an ink tank removably mounted to the recording head.
Recently, the ink jet recording device increases the range of its use. A number of ink jet recording units of the type which is formed with a recording head and an ink tank removably attached to the recording head are marketed.
In this type of the ink jet recording unit, when the ink tank is set to the recording head, it is necessary to hermetically seal a passage for ink flowing from the ink tank to the recording head, which is located in the jointing portion between the ink tank and the recording head. If the sealing of the ink passage is incomplete, ink leaks outside to give great nuisance to users. Particularly, to the ink tank which uses a portion containing only ink, not the capillary member, the complete sealing of that ink passage is essential.
In many ink jet recording units having the ink tank and the recording head, an O ring is used for hermetically sealing the ink passage for the ink flow from the ink tank to the recording head. An example of the ink jet recording unit using the O ring is disclosed in Unexamined Japanese Patent Publication 6-210869. In the publication, the ink tank is provided with a valve, and an O ring, removably mounted, is used for hermetically sealing the ink passage for the ink flow from the ink tank to the recording head.
The ink jet recording unit using the O ring for hermetically sealing the ink passage has the following problems. To airtightly seal the ink passage in the jointing portion between the ink tank and the recording head, a high pressing force is required. Accordingly, a strong force must be used for detaching the ink tank from the recording head. This impairs an easy handling of the ink jet recording unit. Additionally, a structure for generating the pressure is indispensable for the ink jet recording unit. This leads to complexity of the construction.